| Popis: |
Black chokeberries have a strong mouth-drying effect, for this reason, most of times these berries are used to make jams, juices, purées, jellies, syrups, teas or wines [1]. Pressing juices of these berries generates large amounts of pomace, which usually is discarded or used very inefficiently. For this reason, is very urgent to find a way how to recover high added value bioactives. It is well known that chokeberries are characterized by strong antioxidant properties due to high content of polyphenolic compounds, whereas its pomace is also rich in bioactives, especially anthocyanins, procyanidins, flavonols and phenolic acids; although these pomaces are a good source of lipophilic compounds such as fatty acids, triacylglycerols, tocopherols etc [2]. The aim of this study was to evaluate the possibilities of fractionation of the chokeberry pomace lipophilic fraction during supercritical fluid extraction with carbon dioxide (SFE-CO2) with or without co-solvent ethanol (5%) in two postextraction separators by changing the temperature in the range of subcritical CO2 level at a constant pressure and to characterize the composition of the obtained fractions. SFE with pure CO2 gave a 14% lower yield, while the addition of 5% co-solvent EtOH increased the yield. In the case of SFE with pure supercritical CO2 the highest amount of the total extract was collected in first separator (1S), the remaining in second separator (2S). In the case of SFE with supercritical CO2 and 5% EtOH, the effects of separation were not so negligible; although almost in all cases higher yields were detected in second separator. The antioxidant capacity of extracts and fractions was measured by using an L-ORAC assay which measures the peroxyl radical scavenging capacity of antioxidants which may donate a hydrogen atom. First of all, it may be noted that the ORAC values of lipophilic extracts obtained in first separator by pure supercritical CO2 and 5% co-solvent EtOH were 2 folds higher than those of extracts obtained by supercritical CO2. While in second separator antioxidant capacity was quite similar in both cases. Highly unsaturated TAGs were majorly found in the extracts and fractions. The LLLn constituted 23.26– 24.18%, OLnL 20.35–22.10%, LLnLn 13.20–15.10% and OLL 10.02–12.06%. Four tocopherols (sometimes also called E-vitamers) and 4 phytosterols were preliminarily quantified by their peak areas in the extracts and fractions. It may be observed that, in the case of pure supercritical CO2, the concentration of tocopherols was higher in second separator, while the content of phytosterols was slightly higher in first. The addition of co-solvent 5% EtOH increased the concentration of these compounds in second separator. It might be concluded that, by modifying the supercritical extraction solvent and changing the parameters of the system separators, it is possible to produce fractions of lipophilic substances of various compositions. |
